TOKYO (REUTERS) - United States President Donald Trump on Saturday (Sept 2) spoke by telephone with Japanese Prime Minister Shinzo Abe to discuss the escalating threats from North Korea, the White House said.

The conversation between the American and Japanese leaders came as North Korea said it had developed a more advanced thermonuclear weapon that possesses "great destructive power".

Pyongyang said the weapon would be loaded on a new intercontinental ballistic missile (ICBM) that experts believe has the range to hit much of the US.

"The two leaders reaffirmed the importance of close cooperation between the United States, Japan and South Korea in the face of the growing threat from North Korea," the White House said in a statement.

"President Trump noted that he looks forward to continued trilateral coordination on the margins of the United Nations General Assembly."

Trump spoke to Abe while flying back to Washington after visiting storm-ravaged Houston.